It has been elucidated that bacteria of the genus Bifidobacterium, as with the case of lactic acid bacteria such as Lactobacillus bacteria, have various effects, including improvement of the intestinal flora, bowel movement, and intestinal tract functions, protection against infections, immunostimulation, and caner prevention. These bacteria are believed to contribute to human health through improvements of the enteral environment.
In order to exhibit such effects, the Bifidobacterium bacteria require maintaining a high viable bacterial count in products such as fermented milk. However, because the Bifidobacterium bacteria are typically anaerobic, they have poor viability, and rapidly die particularly in the presence of oxygen.
The applicants of the present application have reported adding an extract of sweet tea (Rubus suavissimus S. Lee) or the like to products that use the Bifidobacterium bacteria such as fermented milk to improve the viability of the Bifidobacterium bacteria in such products (Patent Document 1).
However, while adding an extract of Rubus suavissimus S. Lee successfully improved the viability of the Bifidobacterium bacteria in products such as fermented milk, problem of flavor still remained due to bitterness derived from the Rubus suavissimus S. Lee.